358 BIOLOGICAL EFFECTS OF RADIATION 



9 mill, irradiation at 28 cm., through 0.5 mm. Zn from a tube operating 

 at 200 kv. and 4 ma. He observed partial inactivation of alexin by 

 doses ranging from 0.5 to 4.0 H.E.D. Unfortunately, he omits mention 

 of the concentration or depth of the irradiated serum. For some obscure 

 reason, about the same amount of inactivation was found at all dosages. 

 Such phenomena are, however, not uncommonly experienced by those 

 working on alexin, as is illustrated by the work of Chambers and Russ (34) 

 and of Brooks (28), referred to later. 



Some doubt is cast on all these results with X-rays by the experience 

 of Baermann and Linser (10). These workers X-rayed serum containing 

 alexin, and found it to be inactivated, but when they kept the serum 

 cool, and grounded the container, there was no inactivation. The 

 apparent effect of the X-rays on the alexin was, in reality, a result of 

 heating or perhaps of electrical-discharge phenomena.^ 



Chambers and Russ (34) studied the effects of radium rays on alexin. 

 RaBr2 was used as a source and successive small volumes of serum 

 (32.5 mm.^) were spread in a layer about 1.5 mm. deep on the thin mica 

 plate overlying the thinly spread radium salt. The alpha rays could 

 pass through the mica, and were presumably absorbed for the most part 

 within about 20 n more or less, depending upon the thickness of the mica 

 (unstated) ; the alpha particles from RaC would penetrate about 20 to 

 30 11 further. The nature of alpha-ray absorption is such that no alpha- 

 ray energy acted upon any but this relatively thin layer, at most about 

 3 to 4 per cent as thick as the whole layer. The beta and gamma rays 

 with greater penetrating power were found to be without appreciable 

 effect under the experimental conditions obtaining. 



Under such conditions it is not surprising that inactivation of the 

 alexin was slow, about 40 to 45 hr. being required for half destruction. 

 A peculiar feature of the experiment of Chambers and Russ is the initial 

 lag of the inactivation process. This may have a theoretical significance 

 which will be discussed in detail below in connection with similar results 

 obtained by Brooks. 



Brann (24) also observed slight inactivation of alexin by radiations 

 from RaBr2, but whether alpha radiation was involved is not made 

 clear. 



Theoretical Aspects. — It is manifestly impossible to discuss here the 

 whole physical chemistry of immune bodies. The argument in favor of 

 a simple, primarily stoichiometrical explanation has been forcefully 

 presented by Svante Arrhenius in his " Immunochemistry " and "Quan- 

 titative Laws in Biological Chemistry." It is clear, however, from papers 

 by Madsen and his pupils, cited by Arrhenius, that most toxins are 

 inactivated by heat according to quite definite laws, the time curve of 



^ This is probably the work sometimes referred to as that of "Burmann and 

 Tinsa." 



